Re: Generating all permutations of a list in Haskell

[scwg ( )]

※ 引述《slyfox (klanloss)》之銘言：
: I was tracing the code from:
: http://shivindap.wordpress.com/2009/01/12/permutations-of-a-list-in-haskell/
: but got confused by:
:   permutation [1]
: = [ 1 : permutation [] ]
: = [ 1 : [[]] ]
: where did i go wrong?  Thanks.

permutation [] = [ [] ]
permutation xs = [ x:ys | x <- xs, ys <- permutation (delete x xs) ]

permutation [1] = [ 1:ys | ys <- permutation [] ]
                = [ 1:ys | ys <- [ [] ] ]
                = [ 1:[] ] = [ [1] ]

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                             to share his part of the secret of heaven:
that each affects the other and the other affects the next,
         and the world is full of stories, but the stories are all one.

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◆ From: 128.36.229.73
※ 編輯: scwg            來自: 128.36.229.73        (06/22 02:12)
推 slyfox:thx